John Kerry must show Americans that he is a credible alternative to President Bush

American party conventions have long been among the most staged and scripted of all public spectacles in a country where politics and show business converge more often than is strictly necessary for the health of democracy. Nor will the Democratic Party convention that opens in Boston today strike out in any new direction. It is already destined to be a classic of the genre, with the star-power of the Clintons and the Kennedys raising the curtain in the grand style for the arrival of the presidential nominee, John Kerry, on Thursday.

American party conventions have long been among the most staged and scripted of all public spectacles in a country where politics and show business converge more often than is strictly necessary for the health of democracy. Nor will the Democratic Party convention that opens in Boston today strike out in any new direction. It is already destined to be a classic of the genre, with the star-power of the Clintons and the Kennedys raising the curtain in the grand style for the arrival of the presidential nominee, John Kerry, on Thursday.

This convention is no make-or-break gamble in the sense that it could doom or even weigh down Mr Kerry's campaign. It will be far too carefully orchestrated for that. Four years ago, even the politically tone-deaf Al Gore was helped to a post-convention "bounce" by the energetic oratory of his chosen running mate, Joe Lieberman, and the lingering on-stage kiss he lavished on his wife. Senator Kerry may be no exhibitionist by nature, but he can surely turn in a better convention performance than the former vice-president - especially with the barnstorming southern charmer, John Edwards, beside him.

The question is whether this convention can make John Kerry into a winner - and organisation alone, however inspired and however professional, will not achieve that. Mr Kerry has to come out fighting, and he has to show character. So far, he has done neither. American voters need to know whether this has been a matter of choice - in line with the old adage that if your opponent is destroying himself, you shouldn't interrupt - or whether it reflects serious inadequacies in his candidacy.

Mr Kerry may well have been advised not to raise his head too far above the parapet before the campaign proper is under way - that is, until after the two nominating conventions. And this may have been excellent counsel. The campaign is still young, and any gaffe could be costly. As the weeks have passed, however, it has become increasingly clear that Mr Kerry has a recognition problem. Although his nomination became a foregone conclusion early in the primary process, the polls still indicate that American voters feel they do not know who John Forbes Kerry is, or what he stands for.

To many voters, including many Democrats, this new JFK remains Senator for Massachusetts and Vietnam war hero, but otherwise a blank. He has been unable to project an image of himself across the United States as a national leader in waiting, an attractive and forceful personality who has a well-qualified team and a full slate of well-formulated policies for the country. The great achievement of Bill Clinton in 1992 was to do all this and more in good time for the party convention. No one was left in doubt about either the strength of his personality or his energy and expertise. These qualities eclipsed his manifest defects: his personal lapses and his youth. George Bush owed his very viability as a candidate to his abilities as a campaigner. Where he beat Al Gore, it was thanks to his ability to connect with voters.

That Mr Kerry has so far failed to connect in the same way is not entirely his fault. Until recently, his supporters demanded little more of him than to look capable of beating George Bush. In the campaign so far, however, Mr Bush's misconceived and costly war in Iraq has set almost as many traps for his challenger as it has presented obstacles to his own re-election. War hero though he is, Mr Kerry has a fine line to walk between challenging Mr Bush and appearing unpatriotic.

Mr Kerry's great asset is the fierceness of the antipathy that Mr Bush has awakened through his personality and his policies. This anti-Bush passion was the reason Mr Kerry won the nomination. It could yet win him the election. But he will have to show that there is more to John Kerry than not being George Bush. This week's convention gives him the opportunity to speak to America, and demonstrate that he has the character to lead the nation. It is an opportunity he must not squander.